Milling machine



Jan. 7, 1941. J. B. ARMITAGE Erm. l a 2,227,620

MILLING MACHINE ATTORNEY Jar-.11941. J. B. ARMA-GE mp 2,227,620

MILLING MACHINE l0 Sheets-Sheet 2' Filed Dec. 14, 1936 J. B. ARMITAGEETAL MILLING MACHINE 1o Sheets-sheet s Filed Dec. 14, 1936 Jan. 7, 1941.

J. B. ARMITAGE ETAL MILLING MACHINE Filed Dec. 14, '1936 l0 Sheets-Sheet 4 INVENTORS ATTORNEY Jan. 7, 1941. J. B. ARMI-MGE Erlm.

MILLING MACHINE Filed Dec. 141936 l0 Shee'cs-Shee'fl 5 ATTORNEY.

Jam 7, 1941- J. B. ARMITAGE Erm. 2,227,620

MILLING MACHINE INVENToRs I J/PN/maf E /L/ffrwoop ATTORNEY `Ian. 7,1941. .1.' B. ARMITAGE E1- AL 2,227,620

MILLING MACHINE Filed Dec. 14, 1936 1o sheets-Sheet 7 6.7 f INVENTORS i@JAM/Mfg/m/wm W47 ww? ATTORN EY gan 7 194i J. B. ARMITAGE Erm. 2,227,620

MILLING MACHINE Y Filed Dec. 14, 1956 10 Sheets-Shet 8 BWM WMM ATTORNEYJan.1, 1941. J. B. ARMITAGE mL 2,227,620V

MILLING MACHINE `Filed Dec. 14, 1936 lO Sheets-Sheet. 9

ATTORNEY Jam 7, l941- J. a. ARMI-MGE Erm. 2,227,620

l MILLING' MACHINE Filed D80. 14, 1935 `10 Sheets-Sheet l0 ATTORNEY lioPatented Jan. 7, 1941 UNITED sTATEs 2.227.620 MILLING MACHINE Joseph B.Armitage, Wauwatosa, and Harold L. Heywood, West Allis,`Wis., assignorsto Kearney & Trecker Corporation, West Allis, Wis., a cor-l poration ofWisconsin Application December 14, 1936, Serial No. 115,650

12 Claims.

This invention relates generally to milling machines and moreparticularly to improved actuating and controlling mechanism foravmachine especially adapted to mill surfaces in positions difficult ofaccess.

l A general object of the invention is to provide a milling machine thatis capable of performing milling operations in restricted spaces andthat is adjustable to effect either curved or linear cutting strokes ora combination of both.

Another object of the invention is to provide a milling machineespecially suitable for operating on work pieces presenting restrictedcavities within which milling operations are to be performed.

Another object isto provide an improved workclamping fixture for amilling machine.

Another object is to provide a work-clamping fixture having a pluralityof work clamps and improved mechanism for positively releasing the workclamps.

Another object is to providev a work holding ,apparatus having aplurality of clamps equipped with individual clamping and releasingmechanism and having interconnecting means arranged to apply the forcesexerted by all of the mechanisms to any one of the clamps to release it.1

According to this invention, a milling machine of the type adapted toperform milling operations in close quarters is-equipped with improvedtransmission and control apparatus arranged to facilitate adjustment ofthe mechanism and to coordinate operation of the movable elementsthereof. The ltransmission apparatus includes mechanism for positioningand for effecting feeding movements of a plurality of milling cuttersand mechanism for holding a workpiece and for moving it into cooperatingrelationship with the cutters. The control apparatus includesinterlocking means arranged to prevent relative moverelease theresisting clamp. The work-holding.

clamps have swivelling connections with their actuating pistons inmanner to permit indexing of A lost motion mechanism is so arranged (Cl.Sil-59) the clamped workpiece about its Iclamping axis, and the entirework-holding apparatus may be pivoted about a vertical axis tofacilitate loading. 'I'he foregoing and other objects of this invention,which will become more fully apparent from the following detaileddescription of a preferred embodiment thereof, may be achieved bythe'particular apparatus herein described by way of example inconnection with the illustrations of its structural components in theaccompanying drawings, in which: Y

Figure 1 is a view in front elevation of a milling machine embodying thenovel features of the invention;

Fig. 2 is a top plan view of the milling machine shown in Fig. 1, thetool-carrying slides having been removed to show the top of the mainframe;

Fig. 3 is a view in rear elevation of the milling the left one of thetool-carrying elements partly lin front elevation and partly in verticalsection taken substantially along the plane represented by the line ,4 4in Fig. 2;

Fig. 5.is a view in vertical section of part of the tool-carryingstructure taken along the plane represented by the line 5-5 in Fig. 2;

Fig. 6 is a view of the left spindle-supporting element taken in thedirection of the arrow 6 in lFig. 4, parts having been broken away toshow internal mechanism;

Fig. 'I is a view looking in the same direction as in Fig. 6 but takenin section substantially along the plane represented by the lline 1`1 inFig. 4, part of -the tool-carrying apparatus having been removed;

Fig. 8 is a view similar to Fig. 7 but taken substantially along theplane represented by the line 8 8 in Figl 4;

' Fig. 9 is a view of the tool-supporting and driving mechanism partlyin elevation and partly in sented by the line 9-9 in Fig. 4;

Fig. 10 isa detail view in section taken along the plane represented bythe line Ill-I0 in Fig.

9 showing the adjusting mechanism for the pivindicated in Fig. 9 by thedotted outline show' and l Fig. 16 (sheet 2) is a sectional view of 'thecontrol element taken along the line iG-IS in Fig. 15.

The particular machine illustrated in the drawings as constitutingapparatus disclosing a preferred embodiment of the several features ofthis invention is a milling machine especially adapted for millingarcuate ball raceways,

such as are required in a universal joint of the type shown in PatentNo. 1,522,351 to Carl W. Weiss, although the machine is also applicableto `other uses.

y Referring more specifically to the drawings, and particularly toFigures 1, 2 and 3 thereof, the illustrated milling machine comprises ingeneral a main frame or bed 20 having at each side an inwardly inclinedway, for slidably receiving cutter supporting and driving mechanisms orheads 2l and 22.respectively disposed to cooperate with awork-supporting element 23 mounted on the front of the base 20 andvertically movable relative thereto.

As may'best be seen in Fig. 3, each of the cutter carrying heads orunits includes a driving motor 26 operatively connected to drive a toolspindle 21 whichV carries at its upperend an end milling cutter 28 inposition to operate upon a workpiece 30 held by the work-support- 'ingelement 23. As the surfaces to be machined on the workpiece 30 aredisposed within cavities diiiieult of access and are of non-linearcontour, it is necessary that the cutter-supporting apparatus be madeadjustable to present each of the cutters to the work at a suitableangle and to move the cutters along predetermined paths to form thedesired contoured surfaces. To this end, the' cutter-supporting spindles27 are of tapered construction to permit of opera-- tion in closeproximity to each other, and each driving motor 26 and its associated`spindle 2li is mounted in a unitary frame that is so supported as to beadjustable in several directions.

As may be seen in Figs. 4, 6 and 9, the frame ofeach driving motor 23 issuspended at its top from a pivotal supporting pin, 32 in such mannerthat it may be swung with its associated spindle 2l ,through an arc tochange the angle of presentation of the -cutter 23, as is ing the motorframe in its extreme Upper position. The pivot pin 32 carrying the`frameof the cutter driving motor 25 and the cutter spindie 2l, issupported by a bracket or cradle 33 that is slidably mounted formovement-forward or backward relative to the machine base upon acutter-carrying slide 34, as best shown in Fig. 9. The slide 34 ismounted Afor movement 'towards or from the middle of the machine, as

shown in Fig. 4, 'upon a pivotally mounted oscillating sector or rotarybase 35.

' 35 is rotatably supported by a pivot pin 36,

shown in Figs. 6 7, 8 and 9, upon a main slide 'Ilse sector or slidingbase 31 that slidably engages the inclined way of the frame 20, as maybe seen in Fig. 4.

Movement of the cutters 28 to mill a surface of arcuate contour isaccomplished by turning the sector 35 about its pivot pin 36, as seen inFigs. 7 and 8, and the position and degree of curvature of the arcuatesurface is determined by the positions assumed by the various adjustingslides. For cutting a lineal surface, the segment 35 is held stationaryand the cuttersupportingbracket 33 is moved in a direction 4from back tofront of the machine upon the slide 3d. Chips resulting from the cuttingoperation, andcoolant applied to the cutters, fall down between thecutter heads 2l and'22 into a chip basin or trough 4|, Fig. 2, formed inthe main frame 20, the coolant draining through a screened opening d2into a coolant reservoir formed within the frame 2 0. The accumulatedchips may be removed at intervals through an opening 43 provided forthat purpose in the back Wall of the machine, as shown in Fig 3. 'I'hepower driving mechanism for moving th cutter supporting head through acutting stroke comprises essentially a driving motor 50, shown in Figs.1, 3 and 4, that is mounted on the left side of the frame 23 and isdirectly connected to drive a feed rate changing and reversing mechanism5I from which a main driving shaft 52, Fig. 4, transmits power in thedesired direction and at the desired rate for moving both the cutterhead 2l and the cutter head 22 simultaneously. As shown in Fig. 4, themain driving shaft 52 is connected by bevel gearing 53 to a branch driveshaft 56 associated with the left cutter head 2i, and by bevel gearing55 .to a branchl drive shaft 56 that is associated with the right cutterhead 22. As the driving mechanisms for each. of the cutter heads aresimilar except for being oppositely arranged, the mechanism for the leftcutter head 2|v only is shown in detail as illustrative of thestructure.

As shown in Fig. 4, the branch driving shaftv porting sector 35 aboutits pivot pin 3B. As`

shownA inFig. 7, the shaft 30 is journalled in the main slide 37 and isprovided at its inner end with a bevel pinion 6| that meshes with abevel pinion 62 connected to a worm 33 also journalled in the slide 3l.The worm 63 meshes withworm wheel teeth 6d on the periphery of thesector 35, the arrangement being such that when the worm 33 is rotatedby the shaft 60 and the connecting bevel gearing. the sector 85 will bepivoted about the pivot pin 3S in manner to move the milling cutter 23through an arcuate path.

In order that the sector 35 may be turned' manually in. adjusting themechanism, the outer end of the shaft 3@ is provided with a squaredportion 55 for receiving a hand crank. For adiusting the position of thecenter of the arcuate movement of the cutter 23 relative to theworkpiece 33, the main'slide 3l may be moved along the. ways on theiframev 20 by means of a threaded shaft 63 which is lIournalled in theframe. as shown in Figs. 2 and 5, and thathas threaded engagement with anut 81 formed on and depending from the slide 31, a squared end portion68 being provided on the shaft 88 for receiving an adjusting crank. Theshaft 88 has splined connection with the gear 59 in the gear box 51 topermit of sliding movement therebetween when the main slide 31 is movedrelative to the frame l28, and clamping bolts 89 are provided forclamping the main slide to the frame in the adjusted position.

When it is desired to move the milling cutter 28 in manner to effect alinear cutting stroke, the gear couplet 58 'on the driving shaft 54 ismoved to its upper position at the outer end of the shaft by means of ashifting` lever 18 (Fig. 3) in manner to mesh with a gear couplet 1|-journailed in the gear box 51 concentric with the shaft 68 and whichhas meshing engagement with a gear wheel 12 mounted on a shaft 13journalled in the upper part of the gear box. As shown in Fig. 8, theshaft 13 is connected by a flexible drive 14, including two universalJoints and an intermediate telescoping shaft, to a short shaft 15 thatis journalled in a bracket carried by the slide 34 which is mounted onthe 'sector 35. The shaft 15 is provided at its inner end with a bevelpinion 16 that meshes with a bevel pinion 11 on the end of a threadedfeed shaft 18 (Fig. 9) that is journalled in the slide 34 and thatengages a nut 19 depending from the cutter supporting cradle 33, wherebythe cradle and Sthe cutter driving motor 28 carried thereby may `\bemoved transversely of the slide 34.

The feed rate changing and reversing mechanism for regulating the rateand direction of movement of the milling-cutter 28 in'its feeding strokeis shown in detail in the expanded view, Fig. 11. 'As there shown, thedriving motor 58 is connected to a driving pinion 8| that meshes with agear wheeel 82 on a main or clutch shaft 93. 'I'he main shaft 83 carriesa reversing mechanism including a gear wheel 84 mounted on anti-frictionbearings and that meshes with a gear wheel 85 on a shaft 88 toconstitute a forward feed driving train, and the shaft 83 also 86 in theopposite direction. Shaft extends into a feed rate change gearcompartment accessible by opening a door 98. 'I'he feed changing gearingconsists of a pick-olf gear 9| removably mounted on the end of the shaft88 and a complementary pick-off gear 92 mounted yon the end of a jackshaft 93. The pick-off gears 9| and 92 may be o f any selected ratio totransmit power at the desired rate from theshaft 88 to the shaft 93,there being a pinion 94 o'n the shaft 93 which engages a gear wheel 95onthemain driving shaft 52. e

To provide for selecting the direction in which the cutter 28 is movedand for reversing the movement of the cutter at the vend of a cuttingstroke, the gear wheels 84 and 81 rotatably mounted on the mainshaft 93are arranged to be selectively connected 4to the shaft 83 by frictionclutches 98 and 91 respectively. The friction clutches 98 and 91 arearranged to be engaged alternatively, to operate the cutter drivingmechanism in the one or the other direction, by means of a fluidpressure actuated device including a piston element |83 that is slidablymounted on the shaft 93 between the clutches and arranged to be normallyurged to a central position therebetween by means of a detent mechanism|84. To engage the clutch 98 for driving the mechanism in forward feeddirection, fluid pressure is admitted to a chamber |85 at the right endof the piston |83 through a passageway |88 that extends longitudinallyof the shaft 93 to the right end thereof,`the fluid pressure serving tomove the piston |83 to the left, as seen in Fig. 11, and to force theplates of the clutch 98 into engagement. vTo engage the clutch 91 fordriving the meclianism in Areverse direction, fluid pressure is admittedto a chamber |81 at the left side of the piston |83 through a passageway'|88 extending longitudinally of the shaft 83 to the left end thereof.By reason of the fact that the piston 83 acts directly on the plates ofthe clutches 98 and 91 under the influence of the fluid pressure, theapparatus is self-adjusting tocompensate for any wear to which theclutch plates may be subjected. When pressure is relieved from both thechamber |85 and the chamber |81, the detent mechanism |84 returns thepiston |83 to the central position, in which position both of.-

the clutches are disengaged.

The driving mechanism for rotating the cutter supporting spindle 21comprises a worm |28 secured on the shaft of the motor 28 and thatmeshes with a worm wheel |2| fixed with the spindle 21, as shown inFigs. 4 and 9. The worm wheel |2| is provided with a relatively longsleeve |22 encircling the spindle 21 and constituting a re-inforcingmember for stifi'ening the spindle. As shown in Fig. 9, the spindle 21is rotatably supported within a tapered housing |23 that is attached toand constitutes part of the frame supporting the motor 28 and movestherewith as a unit in pivoting about the pivotal supporting pin 32.

In order that the two spindles of the milling machine may operate closetogether in performing certain milling operations, th'ehousing |23 ofeach spindle is made in a shape. tapering toward the cuttersupportingend of the spindle. As near as possible to thercutter receiving end ofeach spindle, there is provided an anti-friction bearing |24 comprisingan outer race |25 mountled in the tapered end of the housing and aninner race |28 formed integrally with the spin- 'V dle, together withcooperating anti-friction rollers |21 disposed between the outer and theinner races. By forming the inner race |28 integrally with the spindle,the diameter of the bearing |24 is reduced to the minimum and it ispossible to place it nearer to the cutter-receiving end of the spindlethan would be thecase if the inner race were formed separately andfitted over the spindle. The spindle 21 is supported at its other end byan anti-friction bearing |28 carried in a cap |29 fitted in the otherend of the housing |23. The cutter receiving end of the spindle is oftapered external contour and is provided with a tapered shield |38protecting the bearing and with a cylindrical cutting shank receivingsocket |3| for receiving the cutter 28. The shank of the cutter 28 isprovided with a flat side |32 that engages a driving key |33 in thespindle to pre- .vent -rotation of the cutter relative to the spindle.

Two set screws |34 and |35 are provided in the spindle for engaging theflat surface|32 of the sate for change in the length of the cutterresulting from sharpening it, there is provided a positioning rod |31,extending longitudinally through a central bore of the spindle 21 andarranged to engage with its forward end the inner end of the cuttershank. The rod |31 has threaded engagement with the other end of thespindle in such manner that rotation of the rod relative to the spindleresults in adjusting the cutter 28 longitudinally of the spindle. Forindicating the amount of movement of the cutter relative to the spindle,the adjusting rod |31 is provided at its outer end with a cylindricalindicating dial |38 having graduations disposed to cooperate with anindicating pointer |39 on a cylindrical member |48 in such manner'thatthe cutter may be moved either inwardly or outwardly by a predeterminedincrement. The cylindrical member |40 is mounted to rotate with thespindle 21 and constitutes also an adjusting nut for adjusting thespindle bearings. After the cutter 28 has been adjusted, it may belocked in position by tightening the set screws |34 and |35 and thepositioning rod |31 may be locked in position by means of a lockingmechanism' |4| in the exposed end thereof.

For positioning the cutter 28 angularly to adapt it for engaging aworkpiece, the cutter driving unit may be pivoted about the pivotalsupporting pin 32 by means of a pinion |55 that is disposed to mesh witha gear segment |36 formed Apivot pin 32 and by tightening bolts whichengage in an arcuate T slot |58 at the back of the motor frame. Furtheradjustment of the position of the cutter 28 relative to the workpiece orto the center of the pivot pin 38 may be accomplished by moving thesupporting bracket 33 relative to the slide 34 by means of an adjustingcrank applied to a squared end |5| of the threaded shaft 18 shown inFig. 9, and the siide38 may be adjusted in a direction at right anglesto the shaft 18 by means of a threaded shaft |52 shown in Fig. 4, thatis journalled-in a bracket carried by the Islide 34 and has threadedengagement with a nut |53 mounted on the pivoted sector 85, the shaft|52 having a squared end |54 for receiving an adjusting crank. Clampingbolts |56 are provided for clamping the bracket 83 to the slide 38, andother clamping bolts |51 clamp the slide 33 to the arcuate sector 35. Tomachine an arcuate contour on a workpiece, the cutter 28 is set at aproper angle to engage the work and at the proper distance from thepivot axis of the sector 35 by the various adjustments just explained,and the pivotal axis is adjusted relative to the workpiece by moving themain slide 31 as previously portingelement 23 comprises a knee portion|63 that is slidably mounted in vertical ways |68 on the front of themain frame 20, and that may be clamped rigidly thereto in the usualmanner in the position to which it is adjusted by the elevatingmechanism |6|i. Pivotally mounted upon the knee |53 for movement about avertical axis is a Work-supporting head or saddle |65 that is arrangedto be turned from the operating position shown in Fig. 2 through ninetydegrees in counterclockwise direction to a loading position. Pivotalmovement of the head |65 is effected by means of a piston |66, shown inFigs. 12 and 14, that operates in a cylinder |61 mounted on the knee|53. The piston |66 is attached to a piston rod |68 provided with rackteeth |88 that mesh with a pinion |13 secured to a depending hub portion|1| of the head |65 that is journalled in the knee |63 by ananti-friction bearing |12. Movement of the pivoting head |85 to theoperating position is limited by a positive stop |15 (Fig. 1) on theknee which engages the head and accurately positions it to support theworkpiece in alignment with the cutters. Another similar positive stop|16 is provided at the other side of the knee for stopping the head inthe loading position. After the head has been pivoted to the operatingposition, it may be rigidly clamped by means of a circular clamp |11that engages a gib |13 and that is actuated by a clamping lever |19 atthe left side of the knee.

The pivotally mounted head |55 supports a work-holding fixture |88 thatis slidably mounted thereon for linear movement toward or from thecutters. As shown in Fig. l2, the fixture |88 has connected to it apiston rod |8| carrying a piston |82 that operates within a cylinder |83formed in the rotatable head |65. Sliding movement of the fixture iseffected by admitting fluid under pressure to the cylinder |83 at one orthe other side of the piston |82.

The forward nose portion of the fixture |88 is arranged to rotatablysupporta work holder |85 that may be turned about a horizontal axis toposition the workpiece for successive cutting operations. As shown inFig. 12, the Work holder |85 is in the form of a sleeve journalled inthe xture |89 and is provided with an encircling bevel ring-gear |86that meshes with a bevel pinion |81 (Fig. 13) carried on an indexingshaft |88 that is journalled in the fixture B88 at right angles to thesleeve and is provided at its outer end with an indexing crank |89, thegear ratio being such that four turns of the crank |88 result in onecomplete revolution of the work holder |85.

The work holder |85 is provided with two separate clamps for engagingthe workpiece 38 at spaced positions, each clamp being independentlyoperated in such manner that they exert substantially equal clampingpressures. As shown in Fig. 12, the work clamp comprises a forward splitcollet |92 that is supported within the forward end of the work holder|85 against a retaining ring |83 in position to engage a cylindricalporshape. The two collets |92 and |94 are arranged in abuttingrelationship and the inner collet is engaged by a retaining ring I 95that is supported from the work-holding sleeve |95 by means of pins |96in such manner as to hold the collets against each other and against theretaining ring |93 to prevent endwise movement thereof As shown, both ofthe collets |92 and |94 are provided with tapered external surfaces forengagement by complementary actuating sleeves |98 and |99 respectively,the sleeve |99 being positioned within the sleeve 199. 'I'he sleeves |99and |99 are also split longitudinally to provide for circumferentialresilience and' they are so arranged that upon movement toward theforward end of the work holder, they co-act with the tapered surfaces ofthe cooperating split collets |92 and |94 to cause them to contract andgrip the workpiece. The outer actuating sleeve |99 is arranged to beoperated by a cylindrical sleeve 20| which is operatively connected toit by an anti-friction thrust bearing 202 constituting a swivellingconnection permitting the sleeve |99 to turn with the work holder |95during indexing operations while the sleeve 20| remains stationarywithin the body of the mixture |90.

For moving the sleeve 20| longitudinally to effect clamping action ofthe collet |92, there is provided a piston 203 which is attached to theend of the sleeve in position to operate within a cylinder 204 attachedto the back of the fixture |90 in co-axial relationship with theclamping collets. For moving the inner actuating sleeve |99 there isprovided a cylindrical sleeve 201 arranged to operate within the sleeve20| and having' swivelling connection with the actuating sleeve |99 bymeans of an anti-friction thrust bearing 209. The sleeve 201 is likewiseprovided with a piston 209 which is arranged to slide within acylindrical inner surface of the piston 203, the arrangement being suchthat when the fluid pressure is appliedto the back of the pistons in theouter end of the common cylinder 204, both the piston 203 andthe piston209 will be moved forward independently of each other to applyindependent self-locking clamping action upon the two portions of theworkpiece by the respective collects |92 and |94.

For positioning the workpiece 30 in the work holder, there is provided apositioning fixture or gauge 2.| that is' pivotally supported on a4 bar2|9 adjustably mounted on the top of the workholding fixture |90 in suchmanner that it may be swung down into work-engaging position as shown inFig. l2, or turned upward to an inactive position as shown in Figs. 1, 2and 3. When the fixture 2|5 is in the position shown in Fig. 12, it isadapted to engage the end of a workpiece 30 by means of a plain stopsurface 2|1` extending transversely of the axis ofv the` 2|5, theclamping collets |92 and |94 are contracted to grip the workpiece byadmitting fluid pressure to the right end of the cylinder 204 and thepositioning fixture is then swung up to its inactive position.

vFluid pressure for actuating the clamping pistons and for operating theother fluid actuated parts of the machine is provided by a pump 225 thatits directly connected to the end of the shaft of the driving motor 50,as shown in Figs. 4 and 1l, for operation thereby to withdraw liquidfrom a sump 226 in thebottom of the main frame 20 by means of a suctionpipe 221. Referring to the circuit diagram in Fig. 14, liquid underpressure from thepump 225 passes through a conduit 228 into a'pressurerelief valve 229, which serves to limit the pressure in the conduit to apredetermined maximum -and to permit any excess liquid to flow throughaconduit 230 into a return conduit 23| which leads back to the sump 229.From the relief valve 229, the pressure liquid passes through a conduit232 into a by-pass valve 233, from which it flows through -a conduit 234to a work-clamping valve 235. To clamp the workpiece, a clamping lever239 on the valve 235 is moved from the position shown in dotted lines tothe solid line position, thereby admitting uid from the valve 235through the conduit 231 thence into the return conduit 23|.

After the workpiece has'been clamped in the work holder, the pivotallymounted supporting head is turned in clockwise direction to operatingposition. For this purpose, liquid under pressure flows from the by-passvalve 233, which functions to permit the liquid to pass into a conduit24| from which a branch line 242 leads to a controlvalve 243, thearrangement being s uch that should the pressure in the system dropbelow a predetermined minimum, the 'ny-pass valve 233 will close theconduit 24| to conserve the remaining liquid pressure for acting'on thework clamping mechanism. The valve 243 controls the swinging or pivotingmovement of the work-'holding head |95 and it is actuated by a 4camplate 244 which may be turned by an operating -lever 245, shown in Fig.l5, to any one of three-positions, a detentV mechanism 249, Fig. 16,being provided to retain the 'cam in the selected position. The camplate 2441s provided with acam groove 241 that engages a cam follower249 on the operating stem of the valve 243. The shape of the cam groove241 is such that when the operati-ng lever245 is moved from the positionA, shown in dotted lines, to the dotted line position B; the valve 243will be positioned to admit pressure fluid through a conduit 250 to theinner or left end of the cylinder |91, thereby forcing the piston |99Yto the right and -turning the worksupporting head |95 clockwise from'the loading position to the operating position. Fluid in the outer orright end of the cylinder |91 escapes through a series of exhaustopenings 25| into an As the pivoting head |95 through an auxiliarypassageway 255 having a constricted portion 255' of such limitedcapacity that the final movement of the work-supporting head intoworking position occurs veryslowly in order that the head may engagelthe positive positioning stop |15 without shock. After thework-supporting head |65 has been turned to working position, it isclamped by actuating the clamping lever |19 to engage the circular clamp|11 with the gib |13 on the hub |1| of the head, thereby drawing thehead down tightly upon the top of the knee |63.

To advance the workpiece .to the cutters, the operating lever 265 maythen be moved from position B to position C, .the shape of the camgroove 221 lbeing such that 'no change occurs in t-he position of thevalve 2&3. In moving the llever from position B to position C, a secondcam groove 256 in the cam plate 24E acts upon a cam folllower 251 on thestem of a control valve 258 in manner to position the valve foradmitting pressure luid, flowing to it from the conduit 22| through abranch conduit 259, into a conduit 260 that leads to the right end ofthe cylinder |83 to move the work-holding xture |811 forward ,toward thecutters. As the fluid is admitted into the right end of the cylinder|83, it forces the piston |82 to .the left and the fluid in the left endof the cylinder escapes through a rapid traverse rate passageway 26| anda feed rate passageway 262, both of which lead to an exhaust conduit 263through which the exhaust fluid returns to the valve 258 and thencethrough a conduit 28d to the conduit 253 and the return conduit 23|leading to ythe .sump 22%. Both .the pressure conduit 26@ and theexhaust conduit 263 pass through a cylindrical piston 265 .that ismounted in the center of the hub |1| and that constitutes a rotatableconnection with the swinging head |55.

The arrangement is such that the fluid pressure acting on the right endof the piston |32 causes the workpiece 3|) to advance toward the cutters28 at rapid traverse rate. As theA workpiece approaches the cutters. anadjustable actuating rod 21@ carried by a bracket 21| that is mounted onthe piston rod |8l, moves into contact with a cut-ofi valve 212, whichis slidably mounted in the iixture in cooperating relationship with therapid traverse passageway 26|, and is heldin retracted position by aspring 213, the rod moving the valve forward to close off thepassageway, as shown in Fig. 14. After the passageway 26| is closed, allof the escaping exhaust fluid from `the cylinder |83 must pass throughthe feed rate passageway 262 which is provided with an adjustablethrottle valve 21d by means of which the rate of flow of the eX- haustuid may be regulated in order that the workpiece B may be fed againstthe cutters at a predetermined rate to permit the cutters to feed intothe cavities of the workpiece along a linear path. To position thecutters accurately within .the workpiece at the point from which thearcuate cutting stroke is to start, the bracket 21| on the piston rodIBI is provided with an adjustable positive stop sleeve '21S which `isdisposed concentric with the rod 210 and may be set .to abut a stopmember 211 on the head |62 when the workpiece arrives at thepredetermined position.

After the forward feeding movement of the work-holding fixture has beencompleted, the fixture is clamped to the head |55 'by actuating aclamping lever 213 (Fig. 1) to support turn conduit 22|.

the workpiece rigidly in position for the feeding or cutting stroke ofthe cutters 28.

To initiate the cutting stroke, a starting lever 28| associated with adirection-controlling valve.282, as shown in Fig. 14, is actuated tomove a plunger 283 of the valve to its upper postion. With ,the valveplunger 283 in its upper position, pressure fluid from the pump 225 ispermitted to flow by Way of .the conduit 228, relief valve 229 andconduit 222, through a conduit 284 and a passageway 285 in the body ofthe valve 222 to a port 286 and thence through a groove 281 in the valveplunger 28S to a port 288, which.

is connected by a conduit 28% to the passageway i inthe right end of thedriving shaft 83. As previously explained, when pressure fluid isadmitted to the passageway |06, it ows into the chamber |05 and forcesthe-piston |03 to the leit, thereby engaging the forward drivingfriction clutch 9G to cause the transmission mechanism 5| Ito swing thecutting heads 2| and 22 in the forward cutter feeding direction.

During the forward cutting stroke, the cutters 28 each take a roughingcut on the workpiece 3@ along an arcuate path. As the cutting strokeprogresses, a control drum 291|, mounted is rotated in clockwisedirection, as seen in Fig.

14, by a shaft 29| .that is driven by a worm wheel 292 meshing with aworm 223 on the main driving shaft 52 as shown in Fig. l1. At the end ofthe cutting stroke, a reversing trip dog 295 on .the drum 29@ engages apivotally mounted trip lever 298 havingan arm 221 that engages a plunger298 of a reversing pilot valve 299, the arrangement being such ythatwhen the trip dog 2% moves the trip lever 295 to the right, the plunger293 is moved upwardly against the resistance of a spring tit@ .to aposition in which a groove 36| on the plunger communicates with a port3632 in the valve body which is connected with .the pressure duidpassageway 2&35. Pressure fluid from the port to2 then flows along thegroove 32| toal port 323 connected by a passageway Sd to a chamber 25encircling the directional valve plunger 223. Pressure in the chamber305 forces the valve plunger 2t3'downward below the position in which itis shown in Fig. 14, thereby moving a land 32S of the plunger 283 pastthe port 2% to cut od the iiow oi. pressure fluid to the port 222 and topermit iiow thereof through a groove'ili to a port dit@ which isconnected by a conduit @da to the passageway |08 in the left end of theshaft 93. Fluid under pressure from the conduit 32@ passes through -thepassageway |08 into the chamber |01 and forces the piston |63 to Itheright, thereby disengaging the forward feed driving clutch 96 andengaging the reverse driving clutch 21, the iiuid in thechamber |615being forced `out through the passageway |28, the conduit 28@ and valveport 288, to the groove 281 which now connects with an exhaust port 8|@communicating with an exhaust conduit 2| I which is connected to the re-Upon engagement of the re'- verse clutch 91, .the cutters 23 are movedin reverse feed back along 4their arcuate paths to Vtake a finishing cuton the workpiece.

As soon as the control drum 290 has progressed in the reverse directiona sumcient distance to ito 302 and opening an exhaust port 3|2 to permitliquid from the chamber 305to escape through the passageway 304, theport 303, the groove 30|, port 3|2, and a conduit Y3|3 which connectswith the return conduit 23|, thereby releasing the directional valveplunger 283'for movement manually by the lever 28| should it be desiredto stop the feeding movement. As the cutters 28 return through thefinishing cut to their starting positions, the control drum 290 isturned in counter-clockwise direction, moving a stop dog 3I intoengagement with the -trip lever 298. When the stop dog 320 engages thetrip lever and moves it to the left, an arm 32| of the lever engages thelower end of the directional valve plunger 283 and moves it upward tothe neutral position shown in Fig. 14, a detent mechanism 322 beingprovided for retaining the valve plunger in either its central neutralposition or its upper forward cutter feed driving position. As may beseen in Fig. 3, the stop dog 320 is provided with an adjusting screw 323for accurately and rigidly positioning lt. l

When the valve plunger 283 is in-the neutral position, the pressure port288 is closed by the land 308, thereby cutting off the supply ofpressure luid to the reversing clutch mechanism, and the groove 281communicates with the exhaust port 3|0 to permit exhaust liquid from thechamber |05 of the reversing mechanism to flow through the passageway|08, the conduit 289, and port 288, into the exhaust conduit 3H. Alsothe groove 301 communicates with an exhaust vport 325 to permit exhaustfluid from the chamber |01 to iiow through the passageway |08, theconduit 309, and port 308, through the port 325 into an exhaust conduit328 which connects with' the exhaust conduit 3|I.ir This re' suits inrelieving pressure from both sides of the clutch actuating piston |03and in permitting the piston to move to its central neutral positionunder the influence ofthe detent mechanism |04, thereby stopping thefeeding movement of the cutter carryingl heads.

After the nishing cut movement of the c utters has been terminated, theworkpiece may be withdrawn from the cutters for the lpurpose of indexingit to a new position for a second out.

To insure that the workpiece will not be moved while the cutters aremoving through the cut- Iting stroke, almechanical interlockingarrangement is provided, as shown diagrammatically in Fig. 14, and indetail in Figs. 15 and 16. To this end, the feed starting lever 28| ispivotally connected by a link 330 to an interlocking plunger or controlbar 33| that is associated with the control lever 245, the arrangementbeing such thatrwhen the feeding lever 28| is in the neutral position,the control lever 245 may be moved to any of its three positions. Asshown in Fig. 16, the interlocking plunger 33| is provided with a notch332'which is positioned to permit a lug 333 on the lever 245 to passthrough it in turning the cam plate 244 from one position to another,the control bar 33| preventing movement of the lever 245 when the notch332 is not in alignment with the lug 333.`This interlocking mechanismprevents starting the cutting heads through a cutting stroke when thework-holding the work-holding `nxture |80 is first unclan'liped .(as maybe seen in Fig. 3) to the cutters.

by actuating the clamping lever 218 and then the control lever 245 ismoved from position C n to position B, thereby admitting fluid underpressureY from the pum-p 22-5 through the control valve 258 and theconduit 283 to the passage 282 leading to the left end of the cylinder|83, causing the piston |82 to move tothe left at feed rate. AfterY theworkpiece has been moved at feed rate the distance necessary to clearthe cutters 28, the valve plunger 212 is released by' the actuating rod210, and moves outward under the iniiuence of the spring 213, thereby'opening the rapid traverse rate passageway 26| which results in theworkpiece being retracted the remaining distance at rapid traverse rate.The workpiece 30 may then be indexed to its new position, in thisvinstance by turning it through 180 degrees, to present the other sidethereof The 180-degree indexing movement is accomplished by turning theindexing crank |89 through two complete revolutions and then re-engaginga spring-pressed pin 335 on the crank in a socket 338in the body of thefixture |80, as shown in Fig. 13. Turning the crank |89 results in ro- 2tating the work-carrying sleeve |85 within the front of the work-holdingfixture and with it the clamping collets |92 and |94, together withtheir actuating sleeves, the rotation of the sleeves A being permittedby the swiyelling connections afforded by the anti-friction bearings 202and 208. After the workpiece has been indexed, it is clamped in the newposition by actuating a clamping lever 340 after which the work-holdingfixture |80 may be moved forward to engage the work with the cutters asecond time by moving the control lever 245 from the positionV B to theposition C as previously explained. The fixture is then clamped by meansof the lever 218 and the second cutting stroke is started by means ofthe starting lever 28|, the mechanical interlock being so arranged thatwith the lever 245 at position C, the lug 333 is disengaged from thenotch 332.

After the second cut has been completed and the directional valve 283and its lever 28| have been returned to stop position, the notch 332 isagain brought into alignment with the lug 333 to' permit movement of thecontrol lever 245.

'Ihe clamp lever 218 is then operated to unclamp the sliding fixture 80and the control lever 248 i and the control lever 245 is then moved fromposition B to position A to position the `control valve 243 foradmitting pressure fluid through the conduit 252 to the right end of thecylinder |81. thereby forcing the piston |88 to the left and turning thework head 'counter-clockwise, as seen inFig. 2, to the unloadingposition. Liquid in the left end oi' the cylinder |81 escapesV through aseries of exhaust openings 35|, which are successively closed by thepiston to decelerate the movement, the final movement occurring at slowrate by the escape of liquid throughlan auxiliaryv exhaust passage 355having a constricted portion 356.

After the work-supporting head IBShaS been pivoted to the unloadingposition, the Workclamping lever 236 is actuated to unclamp theworkpiece 30 by positioning the valve 235 in manner to admit pressurefluid through the conduit 238 to the left end of the cylinder 204. Theuid pressure in the left endv of the cylinder urges the piston 203 tothe right and also exerts pressure on the piston 209 independently byreason of the fluid passing through passageways 360 in the piston 203 toact upon the face of the piston -209. Movement of the pistons 203 and209 to the right, as seen in Figs. l2 and 14, withdraws the actuatingsleeves |98 and |99 from the tapered outer surfaces of the clampingcollets |92 and I9t and permits the collets to expand and release theworkpiece 30. 'I'he pistons 203 and 209 are interconnected by aninterlocking lost motion mechanism in such manner as to permitindependent clamping action thereof and to provide for cooperativeunclamping action. Should either one of the actuating sleeves 98 or |99resist the unclamping action of its asso-` ciated piston,v the lostmotion of the mechanism is taken up by movement of the other piston, andthe force exerted by the pressure uid upon the full area of both pistonsis applied to'release the resisting clamp. For instance, should theinner clamping sleeve |99 resist movement, the outer piston 203 wouldabut againstthe inner piston 209 to assist in the unclamping action. Ifthe cuter clamping sleeve |08 resists, the inner piston 209 in moving tothe right engages a retaining ring 36| in the inner surface of thepiston 203 and exerts force thereon to assist in the unclamping action.After the collets is? and |951 have released the workpiece 30, it may beremoved from the work-holding xture. Any chips or coolant liquid thatmay drop from the finished workpiece at the loading position are caughtin a trough 363 which communicates with the main chip-receiving troughat the center of the frame 20. A fresh workpiece is then inserted in thework holder and clamped therein by actuating the clamping lever 236, andthe cycle of operations just described is repeated.

Although a specific milling machine has been described in detail inorder to clearly disclose the several features of this invention, it isto be understood that the particular apparatus shown and described issusceptible of various modifications that will be apparent to thoseskilled in the art, without departing from the spirit and scope of theinvention as defined in the subloined claims. i

-The invention having beenrfully set forth in the foregoingspecification, we claim:

1. In a power operated work'clamping apparatus for a machine tool, thecombination with a plurality of independently operated work clamps, ofindependent power operated actuating mechanism for each of said clamps,said mechanisms being selectively operative as a group to exert clampingforce or to exert force to positively release said clamps, and lostmotion mechanism interconnecting said actuating mechanisms in manner topermit equalized independent clamping action thereof and to provide forcooperative unclamping action, whereby should a clamp resist beingreleased by its power operated actuating mechanism the lost motion d ofsaid lost motion mechanism will be taken up by movement of an actuatingmechanism of a clamp which has been released and the force of saidsecond actuating mechanism will then be exerted to assist in releasingtheresisting clamp.

2. In a power operated work clamping mechanism, the combination with aplurality of independently operating work clamps, of an independentactuating mechanism for each of said clamps, said mechanisms eachincluding a piston, means for applying pressure to the one or the otherside of each of said pistons for clamping or unclamping work, and lostmotion'mechanism interconnecting said pistons in manner to permitlimited relative movement therebetween for eecting equalized clampingaction, said relative movement being so limited by said mechanism thatthe lost motion thereof is taken up by the actuating mechanism in itsrst releasing movement in manner to effect combined action of all ofsaid pistons in exerting force to release any one of said clamps whichmay fail to release under the force exerted by its operating piston.

3. In a work clamping apparatus for a machine tool, two clampingelements arranged to engage a workpiece at spaced positions, independentmechanisms arranged to operate said clamping elements each of saidmechanisms including an actuating piston, and a common hydrauliccylinder disposed to receive both of said pistons, whereby hydraulicpressure applied to said cylinder exerts equalized clamping forcethrough said pistons and the clamping elements actuated thereby upon theworkpiece at the two positions engaged by said eelments.

4. In a work clamping mechanism for a machine tool, an arrangement forclamping a cylindrical workpiece at two spaced positions simultaneouslyin manner to present one end thereof for machining, comprising a frame,a front split collect supported in said frame, a sleeve slidably mountedin said frame concentric with and outside of said split collet andoperative upon longitudinal movement to slide over and contract saidcollet for gripping a workpiece, an actuating cylinder carried by saidframe, a piston slidably mounted within said cylinder and operativelyconnected to said sleeve in manner to effect actuation of said collet, arear split collet supported by said frame within said outer sleeve, aninner sleeve slidably mounted Within said outer sleeve and outside ofsaid rear collet and operative upon longitudinal movement to slide overand contract said rear collet, and an inner piston operatively connectedto said inner sleeve and slidably mounted Within said outer piston,whereby fluid pressure admitted to said actuating cylinder will causeboth of said collets to be contracted with substantially equalizedclamping pressure.

5. A work holding xture comprising two independently operating clampsadapted to be engaged simultaneously for holding work, power actuatedmeans for engaging each of said clamps independently with predeterminedclamping pressure said power means being selectively operative topositively releasesaid clamps, and an interlocking mechanism associatedwith said clamps and operative upon failure of either clamp to releaseunder the force of its power actuated operating means to apply the forceof the other powerl l actuated means also to said resisting clamp toassist in its release.

6. in a work holding apparatus for a machine tool, means disposed toengage a workpiece at two spaced positions, an independent operatingmechanismconnected to each of said means, an

CFI

independent hydraulic actuating device for each of said operatingmechanisms, and a common hydraulic cylinder for receiving said actuatingdevices, whereby equalized pressure may be exerted by said engagingmeans at the `two positions of engagement thereof with the workpiece. I

'1.l In a work holder for a machine tool, the

combination with power actuated clamping means, of a positioning gaugeremovably disposed to engage and position a workpiece, and a` springurged work engaging means disposed to press the workpiece intoengagement wth'said positioning gauge, whereupon said power actuatedclamp may be actuated 'to grip the workpiece and then said positioninggauge withdrawn to present the workpiece for machining. e'

8. In a work holder, a work supporting fixture. a work clamping deviceon said work supporting fixture for clamping a workpiece theretoincluding. two clamping elements arranged to engage the workpiece atspaced positions', two hydraulic actuating pistons connectedrespectively to actuate said clamping elements independently, and acommon hydraulic cylinder disposed to receive both of -said pistons andoperative to exert equalized clamping force on said clamping elements.

9. In a power operatedwork clamping apparatus for a machine tool, thecombination with a plurality ofindependently operated self-locking workclamps, of an independent power operated actuating mechanism for movingeach of said clamps, said mechanisms being selectively operative as agroup to exert force for locking said clamps or to exert forcetopositively unlock said clamps, and lost motion mechanism interconnectingsaid actuating mechanisms in such manner as to permit equalizedindependent clamping action thereof andl to provide for cooperativeunclamping action, whereby should a. clamp resist being unlocked by itspower operated actuating mechanism, an actuating mechanism of a clampwhich has been unlocked will exert force through said interconnectinglost motion mechanism to assist in.unlocking the resisting clamp.

10. In a machine tool, a power operated Work clamping mechanism adaptedto clamp a workpiece at two positions, the combination with twoindependently operating clamps, of mechanism for actuating said clampsincluding a piston associated with each clamp. means for applyingequalized pressure to one side of each of said pistons for actuatingsaid clamps in manner to exert substantially equal clamping pressures onsaid workpiece at two positions, means for applying pressure to theother side of each'of said pistons for releasing 'said clamps, and alost motion mechanism interconnecting said pistons in such manner thatshould only one of said clamps release upon application of releasingpressure to said pistons, the lost motion of said mechanism will betaken up in such manner that the force 4exerted by both pistons willbecome effective to release the remaining clamp, said lost motion'mechanism being so arranged as to permit equalized clamping action bysaid clamps.

11. Ina power operated work clamping apparatus for a machine tool, aplurality of independently operating work clamps, an independent poweroperated actuating mechanism associated with each of said clamps forexerting force to engage it or to positively dlsengage it, andinterlocking mechanism interconnecting said power actuating mechanismsin manner to permit simultaneous independent clamp engaging actionthereof and to provide for cooperative clamp disengaging action thereof,saidinterlocking mechanism being so arranged that shouldany clamp resistdisengagement by its associated actuating mechanism the actuatingmechanism of a disengaged clamp will exert its force through saidinterlocking mechanism upon said resisting clamp to assist indisengaging it.

12. In a-work clamping mechanism for a ma chine tool, an arrangement forclamping a workpiece at two spaced positions simultaneously in manner topresent it for machining, comprising a supporting frame, a frontcontractable collet rotatably supported in said frame, an outer sleeveslidably mounted in said` frame concentric with said collet andoperative upon longitudinal movement to contract said collet forclamping a workpiece,an actuating cylinder carried by said frame, anouter piston slidably mounted within said cylinder in axial alignmentwith said sleeve, a swivel joint operatively connecting said piston tosaid sleeve for actuating it to contract said front collet, a rearcontractable collet rotatably supported within .said outer sleeve, aninner sleeve slidably mounted within said outer sleeve and operativeupon longitudinal movement to contract said rear collet, an inner pistonslidably mounted within said outer piston, and a swivel jointoperatively connecting said inner piston to said inner sleeve, thearrangement being such that both said front collet and said rear colletmay be rotated for positioning a workpiece without turning said pistonswithin said cylinder and without interfering with the operativeconnections between said pistons and said contractable collets wherebysaid collets are actuated by iluid pressure admitted to said cylinder.

,Y JOSEPH B. ARMITAGEL HAROLD L. HEYWOOD.

CERTIFICATE oF CORRECTION. patent No. 2,227,620. Januar-y 7, 19in.

JOSEPH B. ARmTAGE, ET AI.. 4 It is hereby certified that error appearsin the printed specificationofthe above numbered patent requiringcorrection as follows: lvage, first column, line LLO, for "wheeel" read-wheel; andsecond column, line 65, for the word "cutting" read -cutter;page 5, first column, line'25, for "mixture" read -fixture-; page B,second column, line 55, 'claim 5, for "eelments" read -elements; line59, claim 1I, for "collect" read col1et; and that the said LettersPatent should be read withthis correction therein4 that the same mayconform to the record of the case in` the Patent -Office.

signed and sealed this 11th day of February, A. D. 19in.

Henry Van Arsdale, (Seal) Acting Commissioner of" Patents.

